590 J. Frank Daniel 



The progiess of immunity from the first to the fourth day, while 

 showing various fluctuations, increases with a considerable degree 

 of constancy. This may be shown in the following experiment, 

 which is in general typical for others of the same series. In this 

 the animals were reared in a I per cent medium and tested to 6 

 per cent alcohol on the first, second, third and fourth days of 

 their acclimatization. 



Experiment X 



RESISTANCE OF STENTORS OF TYPE F TO 6 PER CENT ALCOHOL AFTER DIFFERENT PERIODS IN I PER CENT 

 ALCOHOL. A ^ ACCLIMATIZED ANIMALS. C = CONTROLS 



Average resistance = 164 126.5 224 132-5 274.5 '^5-5 ^99-5 '43 



The two extremes — the first and fourth days — are in this experi- 

 ment especially typical. On the third day — as was seldom the 

 case — almost as high a degree of immunity is represented as on 

 the fourth. On this day, as well as on the fourth day of the test 

 example, the control also showed a considerable increase. In 

 both of these cases, however, the degree of increase for the control 

 does not approximate that attained by the acclimatized animals. 



It is thus seen that the same animals kept in a given percentage 

 of acclimatizing medium give different degrees of immunity at 

 different periods of time. 



The variability which was seen to be a prominent feature in 

 beginning immunity is nowhere seen more strikingly than in a 

 study of the maximum degree of immunity. 



